The company has begun sampling 400MHz double data rate SDRAM to chipset manufacturer Silicon Integrated Systems. SiS will test the memory with its SiS648, a new chipset for Intel's Pentium 4 processor. A chipset is a group of chips that support the central processor in a PC.

Dubbed DDR400, the new memory boosts speed 20 percent over its next-fastest sibling, the 333MHz DDR333. It increases peak memory bandwidth from DDR333's 2.7GB per second to 3.2GB per second. The most popular version of DDR SDRAM right now, however, is DDR266, which runs at 266MHz and offers peak bandwidth of 2.1GB per second.

Thanks to higher bandwidth and a faster clock speed, Micron says, DDR400 will be able to keep up with faster, more advanced PC processors and graphics chips that will hit the market later this year. The new memory rivals Rambus' latest 1066MHz DRAM chips, which offer peak bandwidth of 4.2GB per second. These are expected to hit the market this summer.

DDR400 is being tested now; DDR333 has just begun to make its way onto the market through the efforts of chipset makers including SiS, Via Technologies and Nvidia. The companies have all recently announced new chipsets with DDR333 for both Advanced Micro Devices and Intel processors. Meanwhile, their DDR400 offerings, such as the SiS648, won't be far behind.

DRAM maker Samsung is also sampling DDR400.

Meanwhile, Micron--which produces both individual DRAM chips and the modules they are packaged in for PCs--is expected to report a fiscal second-quarter loss of 4 cents a share on revenue of $665.8 million after market close Thursday.

The results are expected be worse than those of last year, but an improvement from the company's first-quarter results, thanks to gains in the ailing DRAM market.

Analysts said Micron's results were helped by higher prices for DRAM chips because of lower supply.

"We believe management comments will be positive, due to a confluence of several positive factors including increased bits-per-box and successive waves of stable pricing increases among the major DRAM players and low inventories in the channel," Thomas Weisel analyst Eric Ross said in a research note.

Micron, the No. 2 DRAM maker by market share, is also continuing its negotiations with No. 3 Hynix Semiconductor for a prospective buyout of Hynix's DRAM manufacturing operations.